Access a Remote Directory from C#

Question

I am trying to access a remote network share from a C# program in asp.net. What I need is something like

function download(dirname)
{
    directory = (This is the part I don't know how to do)

    for dir in directory:
        download(dir);

    for file in directory:
        copyfile(file);

}

My problem is that the directory requires a username and password for access and I don't know how to provide them. Thanks for any help you can offer.